The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
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Volume 64, Issue 2
Displaying 1-3 of 3 articles from this issue
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  • Natural remanent magnetizations of ores and igneous rocks of the Akagane ore deposits, Iwate Prefecture.
    Munetomo Nedachi, Yasumi Abe, Hirotomo Ueno
    1970 Volume 64 Issue 2 Pages 35-52
    Published: August 05, 1970
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.64.35
    JOURNAL FREE ACCESS
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    The Akagane mine is one of the important iron and copper deposits of Japan, mainly of contact metasomatic origin.
    In this study, the igneous rock with which the Akagane ore deposits is connected, is discussed from the paleomagnetic point of view.
    The natural remanent magnetization of the ore and of the igneous rocks around this deposits were measured. The direction of remanent magnetization of the ore and igneous rocks are as follows:
    ore 17°W 64°D
    gabbro 63°W 63°D
    quartz diorite 57°W 66°D
    quartz porphyry 35°W 68°D
    granite porphyry 18°W 66°D.
    According to A. C. demagnetization tests, measurements of the magnetic susceptibility, microprobe analysis and others, the direction of the remanent magnetization of the ore and igneous rocks apeared to be in accordance with that of the geomagnetic field at each mineralization or intrusion period. It is concluded that the direction of the geomagnetic field was in the time of ore deposition very similar to that of the granite porphyry intrusion, but different from the time of intrusion of other igneous rocks, because the geomagnetic dipole was moving gradually in the course of geological time.
    Then, it is suggested that the granite porphyry is the igneous rock with which the ore is genetically related.
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  • Heterogenite from Naganobori Mine, Yamaguchi Prefecture, Japan
    Matsuo Nambu, Katsutoshi Tanida, Tsuyoshi Kitamura, Kin-ichi Sakurai
    1970 Volume 64 Issue 2 Pages 53-63
    Published: August 05, 1970
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.64.53
    JOURNAL FREE ACCESS
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    The first occurrence of heterogenite in Japan is descrived. The mineral occurs as irregular masses, 0.1 to 3cm in diameter, in the oxidation zone of the Naganobori metasomatic cobalt-copper deposit, Yamaguchi Prefecture, associated with goethite, montmorillonite, quartz, malachite and etc. Color steely black, luster dull to submetallic, streak iron gray. Cleavage none. D 3.1-3.4, Vickers hardness 217 (weight 100 gr.). Chemical analysis data coresponds closely to the formula of (Co, Cu) (O, OH)•OH. X-ray study shows the mineral to be rhombohedral with a0 4.72_??_;, α 35°14'. The high-temperature x-ray diffraction and DTA indicate the mineral with some impurities changes to the mixture of CoO, Co3O4, CoFe2O4 and Co2SiO4 at about 1, 000°C.
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  • FORMATION OF VERMICULITE AND KAOLIN MINERAL FROM HORNBLENDE
    KATSUTOSHI TOMITA, HIROSHI TATEYAMA, NOBORU OBA
    1970 Volume 64 Issue 2 Pages 64-71
    Published: August 05, 1970
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.64.64
    JOURNAL FREE ACCESS
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    Vermiculite and kaolin mineral showing a single crystal pseudomorph of hornblende are found in the hornblende andesite distributed in Iriki-cho, northern part of Kagoshima Prefecture. The vermiculite was formed from hornblende and then the kaolin mineral was formed from the vermiculite by weathering. Zoning due to successive argillization is observed in the crystal.
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